Conventionally, shielded cables having a shielding conductor surrounding one or a plurality of center conductors have been used to transmit high-frequency signals. The shielded cable is effective in suppressing the infiltration of electromagnetic noise from a transmission path and in suppressing electromagnetic interference from signal components that leak from the transmission path to a surrounding periphery. Moreover, in order to transmit high-frequency signals with as little attenuation as possible, a shielded cable having a coaxial structure is used.
The shielded cable has flexibility and is therefore easy to handle, and various types of shielded cables are used in many applications. For example, a shielded cable having an extremely small diameter (so-called thin shielded cable) is used inside information devices to transmit digital signals that contain high frequency components.
However, in the case where a shielded cable is used, in addition to electrically connecting the center conductor and the shielding conductor to the object to be connected, the end of the shielded cable must be secured mechanically. To electrically connect the center conductor and the shielding conductor of the shielded cable, an appropriate fastening method, such as a screw, soldering, insulation displacement connection, crimping and the like, is selected. Moreover, in order to secure the end of the shielded cable mechanically, a portion of the insulation jacket of the shielded cable is often removed in advance to expose the shielding conductor. This exposed portion is pressed by a securing bracket into the ground potential area of the object to be connected. This type of method enables the end of the shielded cable to be mechanically secured to the object to be connected and the shielding conductor of the shielded cable to be connected to the ground potential area.
JP 3-030357U discloses a shielded cable connection structure that uses a block-shaped securing bracket to mechanically secure a plurality of shielded cables arranged in a parallel configuration and to connect the shielding conductor of each of the shielded cables to a ground potential area. Moreover, JP 2001-223039A discloses a shielded cable connection structure wherein the center conductor and the shielding conductor of the shielded cable are connected electrically and mechanically to the object to be connected solely by an insulation displacement connection.
Inside an information device, circuit modules are interconnected by small-diameter shielded cables. The small-diameter shielded cables are extremely flexible and are therefore well-suited for ensuring the freedom of layout inside the framework of a small information device wherein circuit modules must be densely deployed. In particular, the shielded cables have a shielded center conductor and are therefore more advantageous for suppressing the generation of electromagnetic interference than the flexible printed circuit boards and the like used previously. In particular, thin shielded cable is highly flexible, and is therefore indispensable for transmitting high frequency signals through a movable part such as a hinge supporting a liquid crystal display unit in a cell phone or camera.
However, as shown in FIG. 8, the prior art shielded cable connection structure for described in JP 3-030357U uses a single block-shaped bracket 6, 8 to secure the shielded cables 9. In order to use this shielded cable connection structure with extremely small-diameter shielded cables, a U-shaped groove having a depth h1 and a width W that are comparable to the outer diameter φD of the shielded cable 9 must be formed in the bracket 6, 8. However, the thin shielded cable wired through the cell phone hinge in the above example has an outer diameter of approximately 300 μm and forming a corresponding U-shaped groove in the block-shaped bracket 6, 8 would therefore be difficult. Thus, application of the shielded cable connection structure described in JP 3-030357U to an extremely small shielded cable would be unrealistic.
Moreover, the prior art connection structure for shielded cable described in JP 2001-223039A uses only insulation displacement connects to connect the center conductor and/or the shielding conductor. However, the diameter of the center conductor of the abovementioned shielded cable with the outer diameter of 300 μm is only approximately 75 μm. As a result, if an extremely small-diameter shielded cable is connected by an insulation displacement connection, not only will an electrically stable connection state be difficult to obtain, but the shielded cable may be damaged. Thus, application of the connection structure described in JP 2001-223039A to an extremely small shielded cable would be unrealistic.